With rapid development of smartphones, a communications module in a wireless local area network (WLAN) is integrated into more mobile communications terminals. On the other hand, as requirements of people for mobile broadband continuously increase, an existing (for example, a wireless cellular) communications system is under greater data traffic pressure.
A wireless cellular network has advantages such as wide coverage and a support for high-speed mobility but also has disadvantages such as a low data rate, a high price, and large transmit power, and is relatively suitable for scenarios such as a high-speed movement and an outdoor wide-range activity. However, a WLAN has advantages such as a high data rate, cost effectiveness, and small transmit power but also has disadvantages such as small coverage, and is relatively suitable for scenarios such as a relatively static scenario and an indoor small-range activity. In consideration of the advantages and the disadvantages of the wireless cellular network and those of the wireless local area network, a feasible method is to integrate wireless cellular technologies with WLAN technologies, and offload data traffic of the wireless cellular communications system using the WLAN in order to improve user experience and implement highly-efficient and cost-effective communication.
Currently, one communications technology is learnt, user equipment (UE) accesses an evolved packet core (EPC) using a base station, and establishes a packet data network (PDN) connection using a packet data network gateway (PDN-GW). Then the UE may access the EPC using, for example, a trusted WLAN access network (TWAN), and the TWAN may select a PDN-GW to establish a PDN connection in order to implement integration of the wireless cellular technologies and the WLAN technologies.
However, the technology cannot ensure service continuity, which greatly affects user experience.